Synthesis of Novel Macromolecular Coupling Agent and its Application in Nano-Copper Lubricating Oil

Background: Due to temperature-insensitive and limited tribochemical reaction, nanolubricants have received tremendous focus over the past few years. The addition of nanoparticles in lubricant has been demonstrated to reduce the coefficient of friction and increase the loadcarrying capability of lubricant in coupled surfaces. Much attention has been paid to copper nanoparticles for their perfect friction reduction and wear resistance performances. However, it is difficult to maintain stable dispersion in lubricant oil for the aggregation of copper nanoparticles. Methods: A novel macromolecular coupling agent copolymer, styrene-butyl methacrylate-3- methoxyacryloyl-propyltrimethoxyl silicon was successfully prepared by free radical polymerization. The structure and composition of the copolymer were characterized through X-ray diffractometer, Fourier-transform infrared spectrometer, and nuclear magnetic resonance spectrometer. The loadcarrying capacities and anti-wear properties of the base oil were evaluated on four-ball tester. Results: The average size of the nano-Cu particle was around 40 nm. The modifier, St-MMA-(KH- 570) macromolecular copolymer could improve the dispersibility of nano-Cu particles. The introduction of the nano-Cu particles helped to improve the tribological properties of base oil. Conclusion: The macromolecular coupling agent was synthesized by free radical solution polymerization method. The modifier was able to bond to the nano-Cu via chemical interaction. The modified Cu nanoparticles as the additive were able to greatly improve the anti-wear and extreme pressure properties of base oil. The optimum concentration of modified Cu nanoparticles in base oil was 0.25 wt.%.